The present invention relates to a distance tracking control system and, in particular, a distance tracking control system for a working member such as a robotic head
There is a need for a distance tracking control system for tracking the distance of a robotic head in relation to a surface of an unknown shape, colour and texture. The robotic head could be mounted on a gantry positioner, or any other type of robotic arm. The system would track the distance between the robotic head and the surface while the robotic head is moving along the surface with a very high speed. Such a system might find applications in space robotics, manufacturing, and the military. The primary commercial application of this distance tracking system will be in laser cutting technology, which application will hereinafter be used to demonstrate the utility of the application.
Laser fabric cutting systems, currently available, have laser cutting heads mounted directly on the beams of gantry positioners, without capability of controlling their focal points. Ideally, to get the best cut by a laser beam, a constant distance must be maintained between the focusing lens and the material to be cut. On the other hand, it is impossible to spread limp material on a cutting table without any waves or bumps. Currently used lenses have about 12.5 cm (5 inch) focal length and, because of focal depth, the system can tolerate up to 5 mm high bumps or waves in the fabric. However, in these places the cut is usually very far from being perfect. A much more efficient way of laser fabric cutting is using lenses with shorter focal lengths (4 cm to 6 cm) that would produce higher energy beams. However, due to the much shorter focal lengths such lenses can accommodate only very small (1 mm) bumps in the fabric. The development of a high speed distance tracking control system will solve this problem, and will allow application of lower power, less costly, gas sealed lasers at additional benefit of much higher quality cut.
A review of the prior art discloses U.S. Pat. No. 4,618,758 by Gilli et al entitled xe2x80x9cFocusing Head for a Laser-Beam Cutting Machinexe2x80x9d. The Gilli reference has a focusing lens which is moved axially by a servomechanism controlled by a position sensor. The position sensor is in sliding contact with the substrate. This sliding contact has a number of inherent drawbacks. In order to maintain sliding contact speed must be limited. In order to maintain sliding contact the substrate must be solid.
What is required is an alternative distance tracking control system.
According to the present invention there is provided a distance tracking control system which includes a non-contact distance sensor for sensing a distance of a movable working member from a surface. An actuator is provided for making positional adjustments of the working member in response to changes in the distance sensed by the non-contact distance sensor. A controller is connected to the distance sensor and the actuator. The controller receives data from the non-contact distance sensor and then sends signals to the actuator to make positional adjustments of the working member.
There are various technologies that can be used to implement the distance tracking control system, as described above; several of which will hereinafter be further described.